Process of inhibiting cracking in re-forming of hydrocarbons



Patented Aug. 7, 1945 PROCESS OF INHIBITING CRACKING RIB-FORMING OF HYDROCARBONS Robert E.

Burk, Cleveland Heights, Ohio, assignor to The Standard Oil Company,

Cleveland,

Ohio, a corporation of Ohio No Drawing. Application January 14, 1941,

Serial No. 374,370

11 Claims.

Where hydrocarbons as of normally liquid character are heated with a catalyst for dehydrogenation or aromatization, cracking or breaking of the carbon chains has also occurred to a disturbing extent. In accordance with the present invention such hydrocarbons may be subjected to heat and catalyst for the special action desired, without incurring the distrubance and losses heretofore customary from associated cracking. Other objects and advantages will be apparent in the invention as the description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described, and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative however, of but a few of the various ways in which the principle of the inven- 1 tion may be employed.

The hydrocarbons to be treated may be of character desired, in accordance with particular conveniences of stocks and results in view, and for instance may be hydrocarbons which are normally liquid, or hydrocarbons of at least six carbon atoms, etc. Such hydrocarbon stock is subjected to heat in a range normally productive of wide scale cracking, such as a temperature of 750-1200 F. and the catalyst may be of detail as desired in'view of the particular effect contemplated as for instance dehydrogenating catalysts and when the stock has over six carbon atoms any aromatizing catalys by which is understood oxides of the metals of periodic group VI mixed with or deposited on a refractory oxide, such as aluminum, magnesium, thorium, silicon, beryllium, etc., and optionally with the presence of smaller amounts of oxides of copper, etc. The pressure in the heating zone may depend somewhat upon the character of products desired, and for instance where molecular conversion of non-benzenoid hydrocarbons to aromatics is required, pressure may be relatively low, as atmospheric up to.200 pounds per square inch, and particularly desirably 50 to 180 pounds. To the heating zone there is also supplied butane hydrocarbon, as butane, or preferably isobutane, or butene in amixture, the butane supply to be in a ratio of 0.25-4 mol per mol of the hydrocarbon being heated. Generally, a ratio of 1:1 is advantageous. A feed'of hydrogen is also supplied to the heating zone, the amount depending somewhat on thetotal pressure employed, and being for instance 1-6 mol of hydrogen per mol of the hydrocarbon being subjected to the heating operation. Desirable practice involves about a 3:1 ratio. Flow rates of hydrocarbon feed exclusive of butane may be 0.1-10 v. v. h. A feed ratio ofone volume per volume of catalyst perhour is in general satisfactory.

In some cases the off-gases from the catalytic zone may contain hydrocarbons of four carbon atoms and under and also hydrogen such as to be capable of being re-cycled and used in the process for a part or all of the butane and hydrogen requirement.

As an example: A vaporized naphtha from 11- linois petroleum is subjected, together with a mixture of isobutane and butane in 1:1 mol ratio, and hydrogen in 3:1 mol ratio, toa temperature of 1025 F. and a pressure of 100 pounds per square inch in a heating chamber in the presence of a 20:80 chromium oxide and aluminum oxide catalyst, the naphtha flow rate being one volume per hour per volume of catalyst. An 80 per cent yield of product showing 84 octane'number is obtained. The raw stock had an octane number of 49. In contrast, where operating to a product of the same knock-rating with the conditions the same except that the butane feed is omitted, the yield of the product is much lower, over 20 per cent lower.

Similarly, a narrow naphtha out including seven carbon atom stock, and a boiling range for instance 172-215 F., is subjected to aromatizing conditions in the presence of an aromatizing catalyst.

By extracting the product with a solvent for the aromatics, as sulphur dioxide, amines, etc., and re-cycling the non-benzenoid portion, the percentage yield of aromatics may be still further raised. o

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims,

or:'the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention? l. Inhibiting cracking in the aromatizing of hydrocarbons, which comprises subjecting a naphtha to a temperature of '750-1200 F. in the presence of an aromatizing catalyst and isobutane supplied in a ratio of 025-4 mols of isobutane per mol of naphtha and, a greater. amount of hydrogen than of isobutane in terms of mols.

, said hydrogen being supplied in a ratio of 1-6 mols of hydrogen per mol of naphtha.

.2. Inhibiting crackingin the aromatizing of hydrocarbons, which comprises subjecting a non-benzenoid hydrocarbon of at least six carbon.

atoms to a temperature 01 750-1200 F. in the presence of a catalyst of 20 moi per cent chromium oxide and 80 mol per cent aluminum oxide and isobutane supplied in a ratio of 0.25-4 mols of isobutane per mol of said non-benzenoid hydrocarbon and a greater amount of hydrogen than of isobutane in terms of mols, said hydrogen being supplied in'a. ratio oi' l-6 mols oi hydrogen per mol of said non-benzenoid hydrocarbon.

4. Inhibiting cracking in the aromatizing of hydrocarbons, which comprises subjecting a nonbenzenoid hydrocarbon of at least six carbon atoms to a temperature of 750-1200" F. in the presence of a catalyst of 20 mol per cent chromium oxide and 80 mol per cent aluminum oxide and a butane supplied in a ratio 01' 025-4 mols or the butane per mol of said non-benzenoid hydrocarbon and a greater amount 01' hydrogen than of butane in terms of mols, said hydrogen being supplied in a ratio of 1-6 mols of hydrogen per mol of said non-benzenoid hydrocarbon.

5. Inhibiting cracking in the re-iorming of hydrocarbons, which comprises subjecting a nonbenzenoid hydrocarbon of at least six carbon atoms to atemperature of 7501200 F. in the presence of a catalyst of 20 mol per cent chromiinn oxide and 80 mol per cent aluminum oxide while re-cycling off-gas providing tour carbon atom hydrocarbons supplied in a ratio of 025-4 mols of the tour carbon atom hydrocarbon per mol of the hydrocarbon of at least six carbon atoms and in the presence of about three times as much hydrogen in terms of mole as four carbon atom hydrocarbons.

6. Inhibiting cracking in the aromatizing of hydrocarbons, which comprises subjecting a non benzenoid hydrocarbon of at least six carbon atoms to a temperature of 750-1200. F. in the presence of an aromatizing catalyst and isobutane supplied in a ratio of 0.25-4 mols of isobutane per mol of said non-benzenoid hydrocarbon of at least six carbon atoms and also in the presence oi hydrogen supplied in amount greater than that of said isobutane in terms of mols, said hydrogen being supplied in a ratio of l-6 mols of hydrogen per mol of said non-benzenoid hydrocarbon of at least six carbon atoms.

7. Inhibiting cracking in the aromatizing of hydrocarbons, which comprises subjecting a'nonbenzenoid hydrocarbon of at least six carbon atoms to a temperature of 750-1200 F. in the presence of an aromatizing catalyst and a butane supplied in a ratio of 0.25-4 mols oi the butane per mol of said non-benzenoid hydrocarbon of at last six carbon atoms and also in the presence or hydrogen supplied in amount greater. than that 01' said butane in terms of mols, said hydrogen being supplied in a ratio of 1-6 mols of hydrogen per mol of said non-benzenoid hydrocarbon of at least six carbon atoms.

8. Inhibiting cracking in the aromatizing of hydrocarbons, which comprises subjecting a nonbenzenoid hydrocarbon or at least six carbon atoms to heat in a temperature range normally productive of wide scale cracking in the presence of an aromatizing catalyst and isobutane supplied in a ratio of 025-4 mols of isobutane per mol of said non-benzenoid hydrocarbon of at least six carbon atoms and also in the presence of hydrogen supplied in amount greater than that of said isobutane in terms of mols, said hydrogen being supplied in a ratio of 1-6 mols of hydrogen per mol of said non-benzenoid hydrocarbon of at least. six carbon atoms.

9. Inhibiting cracking inthe aromatizing of hydrocarbons, which comprises subjecting a nonbenzenoid hydrocarbon 01 at least six carbon atoms to heat in a temperature range normally productive of wide scale cracking in the presence of an aromatizing catalystand a butane supplied in a ratio of 025-4 mols oi. the butane per mol of said non-benzenoid hydrocarbon or at least six carbon atoms and also in the presence of hydrogen supplied in amount greater than that 01 said butane in terms of mols, said hydrogen being supplied in a ratio of 1-6 mols of hydrogen per mol of said non-benzenoid hydrocarbon of at least six carbon atoms.

10. Inhibiting cracking in the re-forming of hydrocarbons, which comprises subjecting a nonbenzenoid hydrocarbon of at least six carbon atoms to a temperature of 750-1200 F. in the presence of a dehydrogenating catalyst while recycling off-gas providingjfour carbon atom hydrocarbons supplied in a ratio of 025-4 mols 01' said four carbon atom hydrocarbons per mol oi.

said non-benzenoid hydrocarbon of at least six carbon atoms, and in the presence of about three times as much hydrogen in terms of mols as four carbon atom hydrocarbons.

11. Inhibiting cracking in the -re-iorming oi hydrocarbons, which comprises subjecting a nonbenzenoid hydrocarbon of at least six carbon atoms to heat in a temperature range normally productive of wide scale thermal cracking in the presence of a dehydrogenating catalyst while recycling oft-gas providing four carbon atom hydrocarbons supplied in a ratio 01 0.25-4 mols oi said four carbon atom hydrocarbons per mol of said non-benzenoid hydrocarbon of at least six carbon atoms, and in the presence of about three times as much hydrogen in terms of mols as four carbon atom hydrocarbons.

ROBERT E. BURK. 

